The present invention is an improvement over the following U.S. Pat. Nos. 3,044,777 dated July 17, 1962; 3,329,430 dated July 4, 1967; 3,201,124 dated Aug. 17, 1965; 1,053,957 dated Feb. 18, 1913; 3,155,753 dated Nov. 3, 1964; 3,044,777 dated July 17, 1962 and 3,193,291 dated July 6, 1965.
Bowling pins now in common use are either made of maple wood, or of maple wood coated with a thin uniform coating of thermo-plastic material. The deficiencies of the all-wooden pins and the uniformly plastic-coated wooden pins are well known by informed people in the trade.
In the first place, the wood from which both types of pins are made is a natural forest product with many random variations in grain strength, depending on the conditions of climate and rainfall affecting growth.
In the second place, as a direct result of the foregoing, both types of pins have a relatively short useful life. Cracking along the grain, in the case of the all-wooden pin or delamination of the plastic coating, in the case of the plastic-coated pin.
In the third place, the entire problem is now seriously aggravated by a shortage of the proper maple wood used in bowling pins.
The logical answer to this problem is a completely synthetic pin, a pin constructed completely of synthetic material, such as plastic of a proper design. But this alone is not enough. In order for the all-plastic pin to be accepted by the trade, two additional attributes must be provided. The first of these is proper action or scorability. This function incorporates the physical characteristics of weight, outside dimensions, balance around a vertical axis, center of gravity, radius of gyration, moment of inertia and coefficient of restitution. The second attribute is that of sound.
The history and tradition of the game of bowling requires that there be no sudden changes in scoring conditions. Past records are constantly compared with present results, and it is essential that no fundamental changes occur that would alter these comparisons. This problem when analyzed and reduced to its essence can be stated in this way: (1) a similar percentage of strikes should occur with a ball thrown in the pocket of a set of pins; and (2) a similar set of pins "leaves" should be expected from a ball which does not strike full in the pocket; and (3) unless the sound is close in character and quality to the wooden pins, the patron will be slow to accept it.